School of Biological Sciences-Microbiology Program, University of Nebraska-Lincoln, Lincoln, NE 68588-0118, USA.
Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, USA.
Viruses. 2020 Jun 23;12(6):678. doi: 10.3390/v12060678.
Chloroviruses are large, plaque-forming, dsDNA viruses that infect chlorella-like green algae that live in a symbiotic relationship with protists. Chloroviruses have genomes from 290 to 370 kb, and they encode as many as 400 proteins. One interesting feature of chloroviruses is that they encode a potassium ion (K) channel protein named Kcv. The Kcv protein encoded by SAG chlorovirus ATCV-1 is one of the smallest known functional K channel proteins consisting of 82 amino acids. The Kcv protein has similarities to the family of two transmembrane domain K channel proteins; it consists of two transmembrane α-helixes with a pore region in the middle, making it an ideal model for studying K channels. To assess their genetic diversity, genes were sequenced from 103 geographically distinct SAG chlorovirus isolates. Of the 103 genes, there were 42 unique DNA sequences that translated into 26 new Kcv channels. The new predicted Kcv proteins differed from Kcv by 1 to 55 amino acids. The most conserved region of the Kcv protein was the filter, the turret and the pore helix were fairly well conserved, and the outer and the inner transmembrane domains of the protein were the most variable. Two of the new predicted channels were shown to be functional K channels.
噬藻体是感染类似绿藻的大型、形成噬菌斑、双链 DNA 病毒，这些绿藻与原生生物共生。噬藻体的基因组大小为 290 到 370kb，它们编码多达 400 种蛋白质。噬藻体的一个有趣特征是它们编码一种钾离子（K）通道蛋白，称为 Kcv。来自 SAG 噬藻体 ATCV-1 的 Kcv 蛋白是已知最小的功能性 K 通道蛋白之一，由 82 个氨基酸组成。Kcv 蛋白与两个跨膜域 K 通道蛋白家族具有相似性；它由两个跨膜 α-螺旋组成，中间有一个孔区，使其成为研究 K 通道的理想模型。为了评估它们的遗传多样性，从 103 个地理位置不同的 SAG 噬藻体分离物中对 基因进行了测序。在这 103 个 基因中，有 42 个独特的 DNA 序列翻译成 26 个新的 Kcv 通道。新预测的 Kcv 蛋白与 Kcv 的氨基酸差异为 1 到 55 个。Kcv 蛋白最保守的区域是过滤器，炮塔和孔螺旋相当保守，而蛋白质的外和内跨膜域则最可变。两个新预测的通道被证明是功能性 K 通道。
